Left adrenal gland thickening of 1cm may be caused by poor lifestyle, long-term medication, endocrine diseases and so on. 1. Adverse lifestyle: partiality and picky eating in diet, resulting in unbalanced nutrition; living in a humid, cold and noisy environment for a long time, which is prone to physical stress, leading to an increase in the secretion of adrenocorticotropic hormone, thus causing adrenal cortical hyperplasia, which is manifested as adrenal gland thickening in the imaging examination. 2. Long-term use of drugs: If long-term use of adrenocorticotropic hormone drugs, can also cause an increase in adrenocorticotropic hormone, resulting in adrenal gland thickening. 3. Endocrine diseases: Some endocrine diseases, such as Cushing’s syndrome and primary aldosteronism, cause excessive secretion of aldosterone, which may also cause adrenal gland thickening. If patients have adrenal gland thickening, it is recommended to go to regular hospitals in time, and carry out standardized treatment after clarifying the cause of the disease, so as to avoid delaying the condition.